This invention relates to the field of querying in network of connected nodes. In particular, the invention relates to assessing response routes in a network of connected nodes.
A network of connected nodes may be provided in the form of a distributed federated database system which is a type of metadata base management system (DBMS), which transparently maps multiple autonomous database systems into a single federated database. The constituent databases are distributed and interconnected via a computer network and may be geographically decentralized.
Through data abstraction, distributed federated database systems can provide a uniform user interface, enabling users and clients to store and retrieve data in multiple non-contiguous databases with a single query, even if the constituent databases are heterogeneous.
This form of query and response may be referred to as peer-to-peer information sharing as the networks provide data from one node to another node within the network.
The database systems may be static or may change dynamically. Ad-hoc dynamic distributed federated databases (DDFD) are known.
DDFDs use a “Store Locally Query Anywhere” mechanism (SLQA), which provides for global access to data from any vertex in the database network. Data is stored in local database tables at any vertex in the network and is accessible from any other vertex using Structured Query Language (SQL) like queries and distributed stored procedure-like processing. The DDFD comprises a set of interconnected vertices each of which is a federated Relational Database Management System (RDBMS) engine. By federated it is meant that the database engine is able to access internal and external sources as if it was one logical database. External sources may include other RDBMS or any other data source as flat files of data records.
DDFDs use distributed database query mechanisms to discover the distributed information sources that can respond to the query and aggregate the information across the network to return a single consolidated result-set to the querying node. This synchronous mechanism quickly finds the nodes that can contribute the required information and returns data to the requesting node by the current ‘fastest route’ but pays the penalty of using a constrained flood query to discover the sources of information.
DDFDs provide distributed data sources, which can be federated across a network of inter-connected self-organising DDFD nodes. In such networks, the data sources and DDFD nodes may be owned by different organisations some of which may be trusted (in some sense) whilst others may be non-trusted. This results in a problem of routes from source nodes passing through untrusted nodes.
In static networks (that are not changing rapidly) a trivial solution to this problem is to centrally determine the structure of the network and to compute the route(s) that minimise the distance between the querying node and the data source(s) via the minimum number of untrusted nodes. A node from which a query is to be launched could query this central system, asking if the data can be sent through a certain route. This central system can hold policy for all of the nodes and there interaction. This approach is not appropriate in the case of a DDFD, due to the dynamic and self-organising nature such systems.
Therefore, there is a need in the art to address the aforementioned problem in dynamic networks.
While the background and description are described in the context of a DDFD, the invention applies to other types of distributed database systems with peer-to-peer information sharing.